In the vehicle side airbag device described in patent document 1 cited below, a side airbag is equipped with a rear side tube bag portion, which extends in an up and down direction on the vehicle rear side of a vehicle width direction outer side end of a chest of an occupant when the side airbag is inflated and deployed, and a front side tube bag portion, which is positioned on the vehicle front side of the vehicle width direction outer side end of the chest of the occupant on the vehicle front side of the rear side tube bag portion and extends in the up and down direction. The upper portion of the rear side tube bag portion is a shoulder restraining portion that is positioned to the side of the shoulder of the occupant and restrains the shoulder, and the upper edge of the front side tube bag portion is an arm support portion that is located in a position lower than the armpit of the occupant on the vehicle front side of the shoulder restraining portion and on which the upper arm of the occupant becomes placed.
That is, in this vehicle side airbag device, the shoulder of the occupant whose load resistance is relatively high is restrained by the shoulder restraining portion, and the upper arm of the occupant becomes placed on the arm support portion, so that the upper arm is kept from coming between the chest of the occupant whose load resistance is relatively low and the airbag.